Gear shift device for an automatic transmission

ABSTRACT

The invention concerns a gear shift device for an automatic transmission, comprising a shift lever ( 1 ) that is pivotally mounted about an axis ( 2 ) in a housing ( 3 ) and inside at least one shift path and that detects and transmits the shift signals electrically, electromagnetically or optically. The shift lever also comprises a locking device ( 4 ) that is guided together with the shift lever along one contour of a block guide ( 5 ) assigned to the gear shift position P, R, N, D and means ( 7 ) that is controlled depending on the speed between at least two positions (active/inactive) and which pivots around an axis ( 6 ). Said means can he pivoted against the locking device ( 4 ) in at least one gear shift position so that the shift lever ( 1 ) remains in the preselected gear shift position or is reset in said position automatically

[0001] The present invention pertains to a shifting device for an automatic transmission according to the preamble of patent claim 1.

[0002] Such shifting devices for the powerless transmission of shift commands to an automatic transmission of a motor vehicle have a gearshift lever mounted pivotably around at least one axis in a housing in at least one shift gate. The gearshift lever detects the shifting signals electrically, electromagnetically or optically and transmits them correspondingly. A locking device, which is guided with the gearshift lever along a contour of a shifting gate, which contour is associated with one of the shift positions (P, R, N, D, . . . ), makes possible the simulation of the individual shift positions for the driver of the vehicle in order to impart a “feeling of shifting” to him. Such a shifting device has been known, e.g., from the patent application DE 197 56 034 A1.

[0003] These prior-art, so-called “shift by wire” shifting devices transmit the shift commands mostly to an electronic control device, which transmits the corresponding shift command to the automatic transmission as a function of optionally preselected parameters when this is permitted by the driving conditions of the vehicle. Thus, there is a permanent set point-actual value comparison. The driver of the vehicle can theoretically select another, actually unacceptable shift position with the gearshift lever during travel without this shift position being immediately transmitted to the transmission, because the permissible parameters, e.g., the speed of the vehicle, do not agree with the gear selected.

[0004] Thus, it would also be conceivable that the reverse gear is selected even though the vehicle is moving forward. However, the automatic transmission would not shift. However, if the preset parameters are reached during travel, i.e., e.g., the speed drops below a certain limit value, the control device transmits the reverse gear selected before by mistake to the automatic transmission and the corresponding gear is engaged. This may lead to accidents, e.g., in intersections.

[0005] The basic technical object of the present invention is to provide a shifting device which effectively avoids shifting errors.

[0006] This technical object is accomplished by the present invention with the characteristic features of patent claim 1. Additional embodiments of the present invention are the subject of the subclaims.

[0007] A shifting device according to the present invention correspondingly has a device, which is controlled in a speed-dependent manner, can be pivoted between at least two positions (active/inactive) around an axis and can be pivoted against the locking device in at least one shift position, so that the gearshift lever remains in the preselected shift position or is automatically returned into that shift position.

[0008] Accidental shifting errors can be effectively prevented from occurring with such a shifting device. The shifting device has a very simple design and the device can likewise be switched or controlled via the central control device.

[0009] According to another embodiment of the present invention, a ramp lever pivotable around an axis is used as the device pivotable between at least two positions (active/inactive), the said ramp lever assuming a position that prevents the accidental selection of the reverse gear during travel in at least one forward gear of the gearshift lever.

[0010] This ramp lever may have a contact surface rising in a ramp-like manner on its side facing the locking device.

[0011] The ramp lever is preferably coupled with an adjusting member, which may be a linkage, an electromagnet or a hydraulically or pneumatically acting adjusting device.

[0012] The adjusting member has an adjusting element, which has variable length, can be pivoted around a mounting point and is coupled with the ramp lever at a spaced location from its axis, so that a change in the length of the adjusting element exerts a leverage acting on the ramp lever, so that the ramp lever can be pivoted between an activated position and an inactivated position.

[0013] Corresponding to a variant of the present invention, the ramp lever assumes an activated position which prevents a shifting error when the speed of the vehicle is higher than a preset limit value of, e g., 5 km/sec and the forward gear (D) is selected.

[0014] The gearshift lever can thus be pivoted only between the shift positions “N” and “D” with the ramp lever activated and the locking device is moved along the rising contact surface of the locking lever with increasing force applied during a movement in the direction of a shifting error, i.e., e.g., from a forward gear into the shift position “R,” so that the gearshift lever will automatically assume the neutral position “N” or the gear “D” selected previously after it has been released by the driver of the vehicle.

[0015] On the side facing the locking device, the ramp lever can have a contour corresponding to a shifting gate at least in some sections. This has the advantage that a changeover between the shift positions “D” and “N” is possible with the ramp lever activated and only the selection of the reverse gear is prevented.

[0016] Corresponding to another embodiment according to the present invention, the locking device may consist of a leaf spring fastened to the gearshift lever, at the free end of which a mount with a contour roller mounted freely rotatably in it is present, which rolls on the contour of the shifting gate. The contour of the shifting gate may have a wave-shaped design in the known manner, with each wave valley corresponding to one shift position (P, R, N, D, . . . ).

[0017] The features of the present invention which were mentioned above and will be explained below can, of course, be used not only in the particular combination indicated but in other combinations as well, additionally or alone, without going beyond the scope of the present invention.

[0018] The embodiment of shifting device which is preferred according to the present invention will be described in greater detail below in a greatly simplified representation based on the drawings.

[0019] In the drawings,

[0020]FIG. 1 shows a view of the interior of a shifting device according to the present invention in a side view in shift position “N,”

[0021]FIG. 2 shows a view of the interior of a shifting device according to the present invention in a side view in shift position “R,”

[0022]FIG. 3 shows a view of the interior of a shifting device according to the present invention in a side view in shift position “D,” and

[0023]FIG. 4 shows a three-dimensional view of the interior of a shifting device according to the present invention in shift position “R.”

[0024] A locking device, designated as a whole by 4, is arranged in the figures at a gearshift lever 1 pivotable around an axis 2 within a shift gate. This locking device comprises a leaf spring 12, whose end forms a mount 13 with a contour roller 14 held therein. The contour roller 14 rolls on a gate-like contour 5 of the shifting device, which is part of the housing 3 in this case. The gate 5 has a wave shape in the known manner, with a shift position (P, R, N, D, . . . ) of the shifting device corresponding to each valley of the wave. Since the shifting device being shown is a so-called “shift by wire” shifting device, the shift positions (P, R, N, D, . . . ) selected by the driver of the vehicle are detected as signals corresponding to the position of the gearshift lever 1 and transmitted to a control device of the transmission, which permanently performs set point-actual value comparisons and energizes the changeover of the automatic transmission only as a function of predefined shifting parameters. Due to this manner of detection and transmission of the shifting signals, there is no mechanical connection to the automatic transmission, so that the driver of the vehicle does not have the “feeling of shifting.” This can be simulated to some extent by the gate 5.

[0025] The shift position “D” is engaged during forward travel, while a changeover to the shift position “N” may also take place when an intersection is being approached. As long as the forward gear “D” is selected, it is theoretically possible that the driver of the vehicle accidentally moves the gearshift lever 1 into an unacceptable shift position (e.g., “R”) by actuating the gearshift lever 1. Since the transmission does not directly receive the corresponding shift command due to the control via an intermediate control device, nothing will happen as long as the predefined parameters are met and recognized by the control device. For example, the reverse gear can be engaged only below a speed of 5 km/hour. This entails needless accident hazards especially during slow travel at intersections, so that a shifting device according to the present invention has a device 7, which is pivoted against the locking device 4 in at least one shift position (e.g., in “D”), so that the gearshift lever 1 remains in the preselected shift position or is automatically returned into this position. A ramp lever 7, which has a contact surface 8 on its side facing the locking device 4, is used for this purpose in the embodiment shown in the figures, with a contour roller 14 projecting laterally beyond the gate 5 sliding along on the said contact surface 8, which is visible in FIG. 4. With the ramp lever 7 activated, the rise of this contact surface causes the further movement of the gearshift lever 1 in the direction of the unacceptable shift position (here “R” or “P”) to require the application of an increasing force and it ultimately prevents the selection of this gear altogether, because the gearshift lever 1 will automatically return into its original position after it has been released by the driver of the vehicle.

[0026] The ramp lever 7 is mounted in the housing 3 pivotably around an axis 6. In its extended section present under the axis 6, it is connected to an adjusting member 9, which is an electromagnet, whose length-adjustable adjusting element (armature) 11 comes directly into contact with the ramp lever 7. The adjusting member 9 is in turn mounted in a mounting point 10 and is slightly pivotable around same.

[0027] The figures differ in that FIG. 3 shows an activated ramp lever 7, i.e., the adjusting element 11 of the adjusting member 9 is completely withdrawn and the ramp lever 7 is pivoted around the axis 6 in the direction of the locking device 4, so that the rising contact surface 8 of the ramp lever 7 prevents the selection of the reverse gear “R” not permitted during forward travel.

[0028]FIGS. 1, 2 and 4 show, in contrast, an inactivated ramp lever 7, i.e., all gears are freely selectable here, which shall be possible at a speed below 5 km/hour. List of Reference Numbers: 1 Gearshift lever 2 Axis 3 Housing 4 Locking device 5 Gate 6 Axis 7 Ramp lever 8 Contact surface 9 Adjusting member 10  Mounting point 11  Adjusting element 12  Leaf spring 13  Mount 14  Contour roller 

1. Shifting device for an automatic transmission with a said shifting device (1), which is mounted in a said housing (3) pivotably around a said axis (2) within at least one shift gate, detects the shift signals electrically, electromagnetically or optically and transmits them, and has a said locking device (4), which is guided with the gearshift lever along a contour of a said gate (5), which said contour is associated with the shift positions (P, R, N, D, . . . ), characterized in that a said device (7), which is controlled as a function of the speed and can be pivoted between at least two positions (active/inactive) around a said axis (6), can be pivoted against the said locking device (4) in at least one shift position, so that the said gearshift lever (1) remains in the preselected shift position or is automatically returned into that shift position.
 2. Shifting device for an automatic transmission in accordance with claim 1, characterized in that the device pivotable between at least two positions (active/inactive) is a said ramp lever (7) pivotable around a said axis (6), which assumes a position that prevents the accidental selection of the reverse gear during travel in at least one forward gear of the said gearshift lever (1).
 3. Shifting device for an automatic transmission in accordance with claim 2, characterized in that the said ramp lever (7) has a said contact surface (8) rising in a ramp-like manner on its side facing the said locking device (4).
 4. Shifting device for an automatic transmission in accordance with claim 3, characterized in that the said ramp lever (7) has a coupling with a said adjusting member (9).
 5. Shifting device for an automatic transmission in accordance with claim 4, characterized in that the said adjusting member (9) is a Bowden cable, a linkage[,] an electromagnet or a hydraulically or pneumatically acting adjusting device.
 6. Shifting device for an automatic transmission in accordance with claim 5, characterized in that the said adjusting member (9) pivotable around a said mounting point (10) has a said length-adjustable adjusting element (11), which is coupled with the said ramp lever (7) at a spaced location from its said axis (6), so that a change in the length of the said adjusting element (11) exerts a leverage acting on the ramp lever.
 7. Shifting device for an automatic transmission in accordance with one of the claims 2 through 6, characterized in that the said ramp lever (7) assumes its activated position preventing a shifting error when the speed of the vehicle is greater than a preset limit value of, e.g., 5 km/hour and the forward gear (D) is selected
 8. Shifting device for an automatic transmission in accordance with claim 6, characterized in that the said gearshift lever (1) can be pivoted only between the shift positions “N” and “D” when the said ramp lever (7) is activated and during a movement in the direction of a shifting error (shift position “R”), the said locking device (4) can be moved along the said rising contact surface (8) of the locking lever only by applying increasing force, so that the said gearshift lever (1) will automatically assume again neutral position “N” or the gear “D” selected previously.
 9. Shifting device for an automatic transmission in accordance with one of the claims 2 through 8, characterized in that the said ramp lever (7) has a contour corresponding to the said gate (5) at least in some sections on the side facing the locking device.
 10. Shifting device for an automatic transmission in accordance with one of the above claims, characterized in that the said locking device (4) comprises a said leaf spring (12), which is fastened to the said gearshift lever (1) and whose free end forms a said mount (13) with a said contour roller (14), which is mounted rotatably therein and rolls on the contour of the said gate (5).
 11. Shifting device for an automatic transmission in accordance with one of the above claims, characterized in that the contour of the said gate (5) has a wave-shaped design, where each valley of the wave corresponds to a shift position (P, R, N, D, . . . ).
 12. Shifting device for an automatic transmission in accordance with one of the claims 2 through 11, characterized in that the said inactivated locking lever (7) is pivoted out of the engagement area of the said locking device (4) around the said axis (6). 